Eu costumo pendurar a toalha para secar, mas hoje vou pendurar o casaco também.

Yes. In Brazilian Portuguese, the subject pronoun is often optional because the verb form already shows the person.

So:

• Eu costumo pendurar a toalha...
• Costumo pendurar a toalha...

both work.

Including eu can add emphasis, clarity, or contrast. In this sentence, eu is perfectly natural, but it is not required.

Costumo comes from the verb costumar, which means to usually do something, to be in the habit of doing something.

So:

• Eu costumo pendurar a toalha = I usually hang up the towel
• costumar + infinitive is a very common pattern.

It expresses habit, not something happening right now.

Because costumar is normally followed by an infinitive.

The structure is:

• costumar + infinitive

Examples:

• Costumo acordar cedo. = I usually wake up early.
• Ela costuma estudar à noite. = She usually studies at night.

So costumo pendurar literally means I usually hang / I’m in the habit of hanging.

Vou pendurar is the near future construction:

• ir + infinitive

It is one of the most common ways to talk about the future in Brazilian Portuguese.

So:

• hoje vou pendurar o casaco também = today I’m going to hang up the coat too

You could sometimes say hoje penduro o casaco também, but vou pendurar sounds more explicitly future-oriented and very natural in everyday speech.

Yes, grammatically it could:

• ...mas hoje pendurarei o casaco também.

But in everyday Brazilian Portuguese, vou pendurar is much more common and more natural in conversation.

The simple future (pendurarei) can sound more formal, literary, or less conversational.

Yes, you can leave it out if the meaning is clear.

Original:

• Eu costumo pendurar a toalha para secar, mas hoje vou pendurar o casaco também.

A more compact version:

• Eu costumo pendurar a toalha para secar, mas hoje vou pendurar o casaco também.
• Or even: ...mas hoje vou pendurar o casaco também is already the shortened natural version after the first clause.

You would not normally say vou também o casaco or something similar. The verb needs to stay in the second clause unless you restructure the sentence more heavily.

Repeating pendurar is natural and clear.

Para secar means to dry or more literally in order to dry.

So:

• pendurar a toalha para secar = hang the towel up to dry

This is a very common use of para + infinitive, which expresses purpose.

Other examples:

• Abri a janela para ventilar. = I opened the window to let air in.
• Saí cedo para evitar trânsito. = I left early to avoid traffic.

Because in this sentence the towel or coat is simply drying, not drying itself in a reflexive sense.

• secar = to dry
• se secar = to dry oneself

Examples:

• Vou pendurar a toalha para secar. = I’m going to hang the towel up to dry.
• Vou me secar com a toalha. = I’m going to dry myself with the towel.

So here secar is exactly the right form.

Portuguese uses definite articles much more often than English does.

So a toalha and o casaco are very natural, even where English might simply say the towel or sometimes no article at all depending on context.

In many everyday situations, leaving out the article would sound less natural:

• pendurar a toalha
• pendurar o casaco

This is normal Portuguese usage.

In this sentence, it most naturally sounds like a specific towel relevant to the situation, such as the towel I usually hang up.

Because of costumo, it can also suggest a habitual routine involving the towel in a general everyday sense. Portuguese often uses the singular definite article in habitual statements where English may also use the.

So the phrase is specific in form, but in context it can describe a repeated action.

Mas means but, and hoje means today.

Together they create a contrast:

• Eu costumo pendurar a toalha para secar = what I usually do
• mas hoje vou pendurar o casaco também = what is different today

So the sentence contrasts a normal habit with an extra action happening today.

Também means also or too.

In this sentence:

• ...vou pendurar o casaco também = ...I’m going to hang up the coat too / also

Putting também at the end is very natural in Portuguese. It emphasizes that the coat is an additional item besides the towel.

You may also hear também in other positions, depending on emphasis, for example:

• Hoje também vou pendurar o casaco.
• Hoje vou também pendurar o casaco.
  This one is less common and can sound more marked.

The original placement is very natural.

Pendurar means to hang. It works very well here.

In Brazilian Portuguese, estender is also common when talking about hanging clothes or towels out to dry, especially on a clothesline:

• estender a toalha
• estender a roupa

The difference is roughly this:

• pendurar = to hang
• estender = to hang/spread out, especially laundry to dry

So pendurar a toalha para secar is correct and natural, but in some contexts a Brazilian might also say estender a toalha para secar.

A very common informal version would be:

• Eu costumo pendurar a toalha pra secar, mas hoje vou pendurar o casaco também.

The main change is:

• para → pra

This is extremely common in speech and informal writing. The meaning stays the same.

Yes. The structure stays the same, but the forms change as needed.

Examples:

• Ela costuma pendurar a toalha para secar. = She usually hangs the towel up to dry.
• Nós costumamos pendurar as toalhas para secar. = We usually hang the towels up to dry.
• Hoje vou pendurar os casacos também. = Today I’m going to hang the coats too.

So the main pattern is:

• [subject] + costumar + infinitive
• [subject] + ir + infinitive

Yes, it is natural and correct.

It combines two very common patterns:

• costumar + infinitive for habitual action
• ir + infinitive for future action

It also uses a very natural contrast:

• usually vs. today
• the towel vs. the coat too

So this is a good, idiomatic Brazilian Portuguese sentence.